Effects of magnitude of reward increment on positive incentive contrast effects in the rat

Abstract

An increase from.01% to 1% in the concentration of saccharine solution in an operant conditioning box with rats produced positive contrast, while an increment from.05% to 1% failed to result in positive contrast effects. These findings are in agreement with the few studies that have examined the effects of magnitude of reinforcement change on the magnitude of incentive contrast with human and infrahuman organisms. It would appear that amount of reward increment is a variable that controls the occurrence of positive incentive contrast effects in rats.